The present invention relates generally to enhancement of growth characteristics of plants and more particularly to improvements in methods and materials for treating seed and seedlings with nucleosides and nucleotides to effect enhancement of emergence and seedling vigor characteristics.
The prior art is rich in proposals of methods and materials for seed, seedling, and mature plant treatment to enhance growth characteristics and resistance of plant tissue to plant pathogens. The materials commonly applied to seed and growing plants range from simple substances such as water (as a pre-planting, hydration treatment for seed), to inorganic salt solutions, to complex growth regulators, antibiotics and the like.
Basic research in plant physiology has included numerous studes of plant cell respiration. Of particular interest to the background of the invention have been studies directed to the role of nucleosides, nucleotides and inorganic phosphate in mitochondrial function, e.g., Holm et al., Weed Science 20: 209-212 (1972); Santarius et al. Biochemica et Biophysica Acta 102: 39-54 (1965); and Hanssens et al., J. Bacteriology 125: 829-836 (1976). These studies are correlated to investigations, by the inventor and others, directed to the agronomic use of purines, pyrimidines, nucleosides and nucleotides as seed treating agents, e.g., Cole et al. Crop Science, 14, 451-454 (1974); and Jung et al., Plant Physiology, 171, 583-584 (1967).
In early 1974, the applicants and their co-workers discovered that the application of nucleosides and nucleotides to seed prior to planting provided salutory effects on overall germination percentages (seedling emergence) and various other indicators of seedling vigor in plants grown from the treated seed. It was found that seeds treated with, for example, adenosine monophosphate (AMP) and cyclic adenosine monophosphate (c-AMP) showed substantial increases in seedling emergence and vigor. The most profound effects were noted in those plants which are extremely sensitive to "environmental stresses", i.e., low temperature and/or high salt and/or soil and airborne pathogens during germination. While the precise mechanism of action of the treatment has not been fully elucidated, it is believed that small quantities of nucleosides and nucleotides are transported through the seed coat and enhance the respiratory efficiency of mitochondria--thus allowing the germinating plant to make more effective use of stored fuel supplies in the seed.
It was unfortunately the case that the emergence and seedling growth characteristics observed for AMP and c-AMP treated seed in laboratory tests were simply not reproducable in field experiments; and, while some degree of improvement was observed as a result of treatment, it was inconsistent and did not appear to justify the treatment materials and processing costs. The reasons for the essential failure of seed treatment to produce the desired effects under field conditions were not known. Prior to the present invention, then, the art had progressed to the stage at which the potential for enhancement of growth characteristics by treatment of seed with nucleotides such as AMP was noted, but no effective means was available to ensure the achievement of such effects under normal growth conditions.